This application claims priority to Korean Patent Application No. 2004-62772, filed on Aug. 10, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates generally to disc reproducing/rewriting systems, and more particularly to defect management therein for defects beyond ECC (error correction code) capability.
2. Description of the Related Art
In general, a system which reproduces/writes information from/to an optical disc such as a re-writable CD-RW, CD-MRW, DVD±R/RW, DVD-RAM, DVD+MRW and so on uses a pick-up unit to access tracks of the optical disc. Manufacturing specifications of the re-writable optical disc guarantee a predetermined number of times for repeatedly rewriting information on the optical disc.
However, with repeated use of the re-writable optical disc, defects may be generated on the optical disc due to deterioration of the disc or other various reasons. Such defects may include a black dot, a scratch, a finger print, etc., as shown in FIG. 1. These defects may be generated in a lead-in region, a program region, or a lead-out region of the optical disc, shown in FIG. 2.
A defect on the optical disc may be fatal such that the defect cannot be handled by an error correction code (ECC) carried out when the optical disc is played. In that case, the optical disc should be discarded in the prior art because the disc is no longer re-writable. In the case of the re-writable optical disc such as CD-MRW and DVD+MRW, information for the start of the optical disc and information about defect management are recorded in the lead-in region. In addition, audio or video data is recorded in the program region, and information for the end of the optical disc is recorded in the lead-out region.
Generally, defects on the re-writable optical disc have been handled in the prior art by ECC which is executed when the optical disc is played. When the optical disc has a minute defect such as a black dot, scratch, or finger print, servo tracking of the pick-up unit is not performed and ECC is executed according to the RS (Reed Solomon) algorithm or the like when an RF signal output from the pick-up unit is decoded to reproduce information from the optical disc.
With increase of recording density of the optical disc, inattentive handling of the optical disc may more easily generate defects. However, a severe defect on the optical disc cannot be repaired by just ECC with suspended tracking, and in that case the optical disc system may not operate properly. Furthermore, the optical disc should be discarded in the prior art when servo tracking cannot be accurately performed even when the optical disc has insignificant defects.
Thus, a mechanism is desired for handling severe defects on the optical disc and when servo tracking is not accurately performed.